1. Field of the Invention
The present invention is in the field of high voltage electronic switches for controllong the discharge of electrical energy from an energy storage device, typically a capacitor or other source, into a load such as an exploding foil initiator (EFI).
2. Description of the Prior Art
Functioning the exploding foil initiator (EFI) in an electronic safe and arm requires a high voltage switch to hold off the voltage on an energy storage capacitor (typically 2-3 Kv for a single EFI) and then upon triggering or initiaiton, produce a fast rise time pulse to the EFI. Typical pulse characteristics are: stored energy of 0.3 to 0.6 m Joules; rise time of 30 to 60 nanoseconds; peak current of 3 to 7 K amps; and peak power of 5 to 15 Megawatts. The most commonly used switch for this application is the ceramic body, hard brazed, miniature spark gap, with either an internal vacuum or a gas filled volume.
A spark gap for this application requires hermetic sealing, is expensive ($50 to $300), has marginal reliability and operating life, and requires an expensive high voltage trigger circuit. The only other known switch in use for this application is the explosively initiated shock conduction switch, which uses a primary explosive detonator which presents handling problems and can produce chemical contamination and possible explosive damage to surrounding electronics.
Other known types of miniature switches include the embedded electrode dielectric breakdown switch (Mound Labs MLM-MC-88-28-000), the reverse bias diode avalanche switch either electrically or light initiated (Quantic Industries and Mound Labs), and the gallium arsenide bulk conduction switch. The embedded electrode dielectric breakdown switch requires a high voltage, relatively high energy trigger pulse from an expensive trigger circuit.
The reverse bias diode avalanche switch requires a significant number of components for both the switch and trigger circuit. The gallium arsenide switch is expensive, may require hermetic sealing, and requires a high power (much more than a laser diode can provide) laser for initiation.
In contrast the invention disclosed herein, a one-shot device, is a very low cost device which does not require hermetic sealing, and can be combined with the EFI and other flexible printed circuit components. Also, the laser diode initiated dielectric breakdown switch can potentially be initiated by a low cost laser diode.